Edmund Gettier
Wikipedia entry on this thinker and his Problem.
FOLDOC: Gettier Problem
Detailed article by Luciano Floridi from this philosophical database.
Is Justified True Belief Knowledge?
Gettier's classic paper from the journal Analysis, 1963.
The Gettier Problem
2001 student paper by Sara Smollett, attempting through improved definitions to recover the definition of knowledge as justified true belief.
UMass Philosophy: Gettier
His official faculty page at the University of Massachusetts. Includes minimal profile.